Relationship Between High Serum Levels of Follistatin with Impaired Physical Function, and Severe Disease Activity in Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is a highly prevalent chronic inflammatory rheumatic disorder leading to functional impairment and sequels. The search for new biomarkers helping in detecting RA subjects of high risk of functional disability is required. Studies showing high follistatin levels in RA have been described; however, none of them have placed focus on the role of follistatin as marker of deteriorated functionality. We aim to identify whether follistatin concentrations could be a potential biomarker of physical disability and disease activity in RA patients. Fifty-seven female RA subjects and 20 age-gender-matched controls were included in a cross-sectional evaluation. An assessment of clinical characteristics, grip strength, gait speed, and muscle mass was conducted. In RA subjects, disability was assessed using HAQ-DI and active disease using the DAS28-ESR. Follistatin levels were measured by ELISA. We compared (a) RA + functional disability and (b) RA + preserved physical function. Serum follistatin levels were increased in RA subjects compared to controls (175 ± 119 vs. 133 ± 47;